Mine came from the powder game were I predicted the day, Called "The Fall" Where The powder game would be over run with noobs. I caused a flame war over it, and "The Fall" Occured soon after.
Mine was a random name for newgrounds called "boxedin", which I edited to "boxmein" for Kongregate. Then it became my awesome internet alter ego #2. First one was werty112(Stole the name from a friend whose ZhyperMU user I played with)(yep, still got the user for it! :3)
A few years ago, I was playing random games on the internet. Often, you needed a name and obviously my name (Joshua) was taken, so I had to think up an internet name. I decided on Jorfor at first, but then decided that sounded retarded so I switched to Jalfor and have stayed with that since.
My name came from a can of spam...my brother kept eating it and i couldnt think of anything else. My other username, ForumTroll, came when i was mad at the world, and just wanted to spam everything :P
I liked the game Incredibots when I was like... 8, so I decided to sign up. Now, I like numbers, so I put "billion" as my username. It said: "Username Taken. Possible Options:"... So one of the options was "billion57," and it sounded nice, so why not?
Well, I wanted to play TF2 once upon a time, but my friend had a second account he didn't use and had TF2 on, so he gave me the password. I played TF2 on it, and use the name for everything else for ease.